INTERGENERIC TRANSFER AND FUNCTIONAL EXPRESSION OF THE TOMATO DISEASERESISTANCE GENE PTO

Plant disease resistance loci have been used successfully in breeding programs to transfer traits from resistant germ-plasm to susceptible p lant cultivars. The molecular cloning of plant disease resistance gene s now permits the transfer of such traits across species boundaries by genetic transformation of recipient hosts. The tomato disease resista nce gene Pto confers resistance to strains of the bacterial pathogen P seudomonas syringae pv tomato expressing the avirulence gene avrPto. T ransformation of Nicotiana benthamiana with Pto results in specific re sistance to P. s. pv tabaci strains carrying avrPto. The resistant phe notype is manifested by a strong inhibition of bacterial growth and th e ability to exhibit a hypersensitive response. Resistance cosegregate s with the Pto gene in transgene selfings and testcrosses. Our results demonstrate the conservation of disease resistance functions across g enus boundaries and suggest that the utility of host-specific resistan ce genes can be extended by intergeneric transfer.